1. Field of the Invention
The present invention provides methods for treating photoresist including methods of forming photoresist relief images having micron and submicron dimensions. More particularly, in one aspect, methods are provided that comprise treating a photoresist coating having a crosslinked surface layer with an organometallic treatment to provide high resolution relief images exhibiting enhanced resistance to plasma etchants.
2. Background Art
Photoresists are photosensitive films used for transfer of an image to a substrate. They may be negative or positive acting. After a coating layer of a photoresist is formed on a substrate, the coating is selectively exposed through a photomask to a source of activating energy such as ultraviolet light. The photomask has areas that are opaque to activating radiation and other areas that are transparent to activating radiation. A relief image is provided upon development of the latent image patterned in the resist coating. The background and use of photoresists are generally described, for example, in Deforest, Photoresist Materials and Processes, McGraw Hill Book Company, New York (1975), and Moreau, Semiconductor Lithography, Principles, Practices and Materials, Plenum Press, New York (1988).
A number of advancements in electronic devices and components have resulted from improvements in manufacturing techniques. Specifically, improvements have occurred in microlithography and in methods of transferring the patterns used to create the complex structures within the electronic devices.
An often preferred method of transferring patterns of micron and submicron dimensions to a substrate is dry etching. The method utilizes plasma or reactive ion etching to remove specific areas of material on a surface so that a pattern remains. Typically the material to be dry etched to create a pattern is a polymeric material for reasons of ease of use, material properties and cost considerations. When an organic polymer is used, dry etching can be done using an oxygen plasma or oxygen reactive ion etching.
During oxygen plasma and/or oxygen reactive ion etching, the organic content of a polymer is converted to a gaseous form which is easily removed. To create the desired pattern, methods have been reported where polymeric material is made resistant to the etching material. See, generally, U.S. Pat. Nos. 4,357,369; 4,396,704; 4,426,247; 4,430,153; 4,433,044; 4,552,833; 4,613,398; 4,921,778; 5,079,131; and 5,108,875.
In U.S. Pat. No. 5,079,131 to Thackeray, et al., a process is disclosed for the formation of positive-tone relief images. The patent discloses, inter alia, subjecting an exposed acid hardening photoresist to treatment with an organometallic material such as a silyl reagent followed by dry development (e.g., oxygen plasma etch) of exposed regions. The organometallic reagent selectively reacts only with unexposed areas of the coating layer and not in exposed or crosslinked areas of the photoresist.
The present invention represents further advances in the art.